Composite fiber

Abstract

Provided is a composite fiber provided with a first fiber structural member comprising a material having a volume resistivity of 5 * 10 <-6 > to 5 * 10 < 6 > [Omega] m or a semiconductor or semimetal material, and a second fiber structural member comprising a ceramic, the first fiber structural member and the second fiber structural member being adjacent to each other to form a fiber body.

Description

Technical Field

[0001] The present invention relates to a composite fiber, and more particularly to a composite fiber composed of at least two fiber structural members. Background Art

[0002] As vibration sensors and actuators that can be used in structures such as buildings, cars, ships, and airplanes, piezoelectric fibers using lead zirconate titanate fibers (hereinafter also referred to as "PZT fibers") are known (for example, Patent Documents 1 to 6). In addition, in order to make such PZT fibers function as stress sensors, vibration sensors, and actuators, smart substrates in which PZT fibers are embedded in structures are also known (for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application No. 2003-12829

[0004] Patent Document 2: Japanese Patent Application No. 2005-171752

[0005] Patent Document 3: Japanese Patent Application No. 2004-15489

[0006] Patent Document 4: Japanese Patent Application No. 2005-59552

[0007] Patent Document 5: Japanese Patent Application No. 2005-313715

[0008] Patent Document 6: Japanese Patent Application No. 2010-198092

[0009] The inventors of the present application noticed that there are still problems to be overcome in the existing lead zirconate titanate fiber (PZT fiber) provided as a ceramic fiber having a ceramic member, and found the need to take measures to solve the problems. Specifically, the inventors of the present application found the following problems.

[0010] For example, Fig.11 As shown in (A) of FIG. 1 , a PZT fiber 100 disclosed in Patent Document 1 or the like includes a PZT thin layer 102 formed by coating a metal wire 101 (a metal thin wire such as a titanium wire or a platinum wire) with lead zirconate titanate crystals (PZT crystals).

[0011] Such PZT fibers can be produced, for example, by growing PZT crystals on the surface of a metal wire using a hydrothermal synthesis method. Alternatively, PZT fibers can also be produced using an extrusion molding method. Fig.12In the extrusion molding method shown, PZT paste 105 (a paste formed by kneading PZT powder, binder, water, and, depending on the situation, organic solvents and various molding additives) is extruded simultaneously with a metal wire 101 to produce a PZT fiber forming body with a metal core wire inserted therein. Subsequently, the PZT fiber forming body is heated, and after undergoing a binder removal process, it is further sintered at a high temperature to produce a PZT fiber having a PZT thin layer formed on the surface of the metal wire.

[0012] Such existing PZT fibers are not necessarily strong enough. Therefore, when used in vibration sensors, actuators, etc., PZT fibers 100 are partially embedded in a structure 202 obtained by stacking CFRP prepreg 201 to reinforce it and use it as a smart substrate 200 (see Fig.11 (B) and (C)).

[0013] For example, when the smart substrate 200 is used as a vibration sensor or actuator, the PZT fiber 100 is a piezoelectric material, and therefore, when vibration is detected, a potential is generated, thereby functioning as a sensor. Conversely, when a potential is applied to the PZT fiber 100, the PZT fiber expands or vibrates in accordance with the potential, thereby functioning as an actuator. Fig.13 As shown in (A), if the PZT fiber 100 is extended in the axial direction indicated by the arrow by applying a potential, then Fig.13 As shown in (B), the PZT fiber 100 can be bent together with the structure 202. In this way, the smart substrate 200 works as an actuator in the following manner: a predetermined PZT fiber among the plurality of PZT fibers 100 functions as a sensor to detect vibration, and the other predetermined PZT fibers suppress vibration (vibration reduction). In addition, Fig.13 In FIG. 1 , the portion of the PZT fiber 100 below the dotted line shows that the PZT fiber 100 is embedded in the structure 202 (specifically, the CFRP prepreg 201) (see FIG. 1 ). Fig.11 (C)).

[0014] When ceramic fibers are used as piezoelectric fibers, such fibers require strength. However, the inventors of the present application learned from the July issue of Polymer Science (Vol. 57 No. 7, 2008) that the strength (tensile strength or elongation at break) of existing PZT fibers is 4 kgf / mm. 2 The fiber strength is still insufficient and needs to be further improved. Summary of the invention

[0015] The present invention has been made in view of such problems. That is, the main object of the present invention is to provide a ceramic fiber having further improved strength.

[0016] The inventors of the present application have attempted to solve the above-mentioned problems by taking measures in a new direction instead of extending the existing technologies. As a result, they have obtained the invention of a composite fiber that achieves the above-mentioned main object.

[0017] In the present invention, there is provided a composite fiber having a volume resistivity of 5×10 -6 ~5×10 6 A first fiber structural member made of a material having a diameter of Ωm and a second fiber structural member made of ceramic, wherein the first fiber structural member and the second fiber structural member are adjacent to each other to form a fiber body.

[0018] From another perspective, the present invention provides a composite fiber comprising a first fiber structural member including a semiconductor or semimetal material and a second fiber structural member including ceramics, wherein the first fiber structural member and the second fiber structural member are adjacent to each other to form a fiber body.

[0019] The composite fiber of the present invention is a ceramic fiber and also becomes a fiber with further improved strength.

[0020] For example, the composite fiber of the present invention is preferably a fiber having a higher strength than the conventional PZT fiber.

[0021] Furthermore, the effects described in this specification are merely illustrative and are not limited thereto, and additional effects may also occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram schematically showing a composite fiber according to one embodiment of the present invention ( Figure 1 (A): Stereoscopic image, Figure 1 (B): Section view, Figure 1 (C): side sectional view).

[0023] Figure 2 It is a cross-sectional view schematically showing a composite fiber according to an embodiment of the present invention, and shows a mode in which a plurality of sub-fiber structural members are arranged as a first fiber structural member.

[0024] Figure 3 Schematic diagram showing a composite fiber (core-sheath structure 1) according to an embodiment of the present invention ( Figure 3 (A): Local excision stereogram, Figure 3 (B): Section view).

[0025] Figure 4 Schematic diagram schematically showing a composite fiber (core-sheath structure 2) according to one embodiment of the present invention ( Figure 4 (A): Local excision stereogram, Figure 4 (B): Section view).

[0026] Figure 5 Schematic diagram schematically showing a composite fiber (multiple cores) according to an embodiment of the present invention ( Figure 5 (A): Local excision stereogram, Figure 5 (B): Section view).

[0027] Figure 6 Schematic diagram schematically showing a composite fiber (first fiber structural member in the form of a microfiber) according to an embodiment of the present invention ( Figure 6 (A): Local excision stereogram, Figure 6 (B): Section view).

[0028] Figure 7 This is a cross-sectional view schematically showing a conjugate fiber (biaxial type) according to an embodiment of the present invention.

[0029] Figure 8 is a schematic diagram schematically showing a composite fiber according to an embodiment of the present invention ( Figure 8 (a): Concentric circle structure, Figure 8 (b): Lateral local excision structure, Figure 8 (c): Lateral half-cut structure, Figure 8 (d): additional construction of the middle layer).

[0030] Fig. 9 It is a perspective view schematically showing a conjugate fiber according to an embodiment of the present invention, and shows a mode in which a first fiber structural member and a second fiber structural member are adjacent to each other in the fiber axis direction.

[0031] Fig.10 It is a perspective view schematically showing a conjugate fiber according to an embodiment of the present invention, and shows a mode having a sandwich structure.

[0032] Fig.11 This is a schematic diagram schematically showing conventional PZT fibers and a smart substrate in which the PZT fibers are embedded in a structure.

[0033] Fig.12 This is a schematic diagram schematically showing an example of a conventional method for producing PZT fibers.

[0034] Fig.13This is a schematic diagram schematically showing a case where a conventional smart substrate is used as a vibration sensor and an actuator. DETAILED DESCRIPTION

[0035] The composite fiber according to one embodiment of the present invention is described in more detail below. Although the description is made with reference to the drawings as needed, the various elements in the drawings are merely schematic and illustrative for understanding the present invention, and the appearance and dimensional ratios may differ from the actual objects.

[0036] The "up-down direction" and "left-right direction" and the like described directly or indirectly in this specification correspond to the up-down direction and the left-right direction in the drawings. In addition, the "cross-section" described directly or indirectly in this specification is typically based on a cross section obtained by cutting the fiber through a plane with the axial direction of the fiber as the normal line. Unless otherwise specified, the same or similar reference numerals, symbols, etc. represent the same or similar components or parts, or represent the same meaning.

[0037] The various numerical ranges mentioned in this specification are intended to include the lower and upper limits themselves unless they are marked with special terms such as "less than", "more than / larger than...". In other words, if a numerical range such as 1 to 10 is used as an example, it can be interpreted as including the lower limit value "1" and also including the upper limit value "10".

[0038] Furthermore, since the fibers described in this specification are referred to as "fibers" in English, it can also be said that the present invention relates to composite fibers.

[0039] The "composite fiber" involved in the present invention refers to a fiber composed of different materials / materials in a broad sense. In other words, the composite fiber of the present invention is typically a fiber composed of fiber structural components of different materials integrated into one. Although "fiber (or fiber body)" refers to an object of such elongated shape that the length dimension is more than 10 times or more than 100 times the cross-sectional dimension in a broad sense, it is not necessarily limited to this case, and the length dimension and cross-sectional dimension can be selected arbitrarily. In a narrow sense, "fiber (or fiber body)" has a size equivalent to the so-called fiber called "fiber", "microfiber" or "nanofiber". Therefore, it can also be that the cross-sectional dimension of the composite fiber of the present invention is, for example, of the order of millimeters, micrometers or nanometers. In addition, the shape of such a "fiber" is not particularly limited. For example, the cross-sectional shape of the composite fiber can typically have a circular, elliptical or rectangular shape, but it is not necessarily limited to this. The cross-sectional profile of the composite fiber as a whole can also be a straight line, a curve and / or a profile formed arbitrarily by a combination of them.

[0040] The composite fiber of the present invention is at least characterized by having a volume resistivity of 5×10 -6 ~5×106 Ωm material" and "ceramic material". In other words, although it is a fiber composed of a ceramic component, the component becomes a "volume resistivity of 5×10 -6 ~5×10 6 Ωm material" composite fiber. In addition, in this specification, "ceramics" can also be referred to as "Ceramics".

[0041] More specifically, the composite fiber of the present invention is formed of at least two fiber structural members made of different materials, preferably having a volume resistivity of 5×10 -6 ~5×10 6 Ωm material and the second fiber structure member is made of a ceramic material. In other words, in a preferred embodiment, the first fiber structure member has a "volume resistivity of 5×10 -6 ~5×10 6 The "material of Ωm" and the "ceramic material" of the second fiber structural member are combined to provide a fiber body.

[0042] The "fibrous structural member" mentioned in this specification refers to an element constituting a fiber body or fiber in a broad sense, and refers to the form of the fiber body / fiber or at least a part of the fiber body / fiber that occupies such a thin / ultra-thin strip shape in a narrow sense.

[0043] The composite fiber of the present invention can also be expressed from other viewpoints. Specifically, the composite fiber composed of at least two fiber structural members of different materials has: a first fiber structural member having a semiconductor or semimetal material and a second fiber structural member having a ceramic. In other words, the "semiconductor or semimetal material" (hereinafter also referred to as "semiconductor / semimetal material") of the first fiber structural member and the "ceramic" of the second fiber structural member are combined to provide a fiber body.

[0044] In the composite fiber of the present invention, the first fiber structure member and the second fiber structure member are adjacent to each other to form a fiber body. For example, when the cross-section is cut through a plane with the axial direction of the fiber as the normal line, the first fiber structure member and the second fiber structure member are adjacent to each other. Preferably, the first fiber structure member and the second fiber structure member are integrated into a single fiber.

[0045] Figure 1 (A) to (C) are examples of the conjugate fiber of the present invention. Figure 1 (A) is a perspective view of a conjugate fiber 10 given as an example. Figure 1 (B) schematically represents Figure 1 The cross section of the composite fiber 10 (a cross section in a direction perpendicular to the axial direction of the fiber) of (A) is shown in FIG. Figure 1 (C) schematically represents Figure 1 The cross section at XX' in (B) (the side cross section along the axial direction of the fiber).

[0046] The composite fiber 10 of the present invention is composed of a first fiber structure member 1 and a second fiber structure member 2. As shown in the figure, the first fiber structure member 1 and the second fiber structure member 2 are adjacent to each other to form a fiber body. In other words, the volume resistivity is 5×10 -6 ~5×10 6 The first fiber structural member 1 having a volume resistivity of 1.0×10 -5 ~1.0×10 6 Ωm or 5×10 -5 ~5×10 5 Ωm, etc. As can be seen from such an explanation, the term "adjacent to each other" in this specification preferably refers to adjacently establishing a positional relationship or contacting each other in order to form fibers. For example, it may also be that, when viewed in section, the first fiber structure member and the second fiber structure member are in close contact with each other to form an interface.

[0047] The "volume resistivity" in this specification refers to the resistivity under the temperature and humidity conditions of 23±5°C and 50±20% relative humidity. Such volume resistivity can be measured in accordance with JIS R 7609: 2007. Although it may be a value obtained by extracting or taking out only the first fiber structural member from the composite fiber and measuring it, for convenience, the volume resistivity obtained as a material before being composited into fibers may also be used.

[0048] The first fiber structural member constituting the fiber body has a volume resistivity of 5×10 -6 ~5×10 6 Ωm, it is preferred that the first fiber structure component is equivalent to a component containing a semiconductor or semimetal material. Here, if it is assumed that the first fiber structure component is composed of a metal material with a lower volume resistivity than the semiconductor / semimetal, on the one hand, the first fiber structure component is based on a metallic bond, and on the other hand, if the first fiber structure component is composed of a semiconductor or semimetal material as in the present invention, the first fiber structure component becomes a component based on a covalent bond. Therefore, for a fiber structure component containing a volume resistivity of 5×10 -6 ~5×10 6For the first fiber structure member of the material / semiconductor / semimetallic material of Ωm, the tensile strength becomes relatively large (that is, becomes larger than that of metal members such as Ti), and a fiber with further improved strength can be obtained. Therefore, a fiber (ceramic fiber) that can be used as a piezoelectric fiber and has a further improved strength can be obtained.

[0049] In a preferred embodiment, such a material comprises a volume resistivity of 5×10 -6 ~5×10 6 The elastic modulus of the first fiber structure component of the material / semiconductor / semimetal of Ωm is relatively high. In other words, the elastic modulus is higher than that of the first fiber structure component composed of metal other than semiconductor / semimetal. Therefore, when a force is applied to the composite fiber, the first fiber structure component can effectively withstand the force. Preferably, when an external force is applied to the composite fiber in order to produce a piezoelectric effect, the first fiber structure component can effectively withstand the applied stress. Therefore, it is not easy to apply inappropriate stress to the second fiber structure component containing ceramics, and as a result, the composite fiber of the present invention can be provided as a high-strength piezoelectric fiber that is not easy to break.

[0050] From this point of view, the composite fiber of the present invention can show high strength and / or high elasticity, and therefore, it is easy to achieve a thinner fiber diameter. The thinner composite fiber (in other words, a composite fiber with a small fiber cross-sectional size) can be more preferably used as a piezoelectric fiber. For example, the composite fiber of the present invention can be provided as a fiber that can obtain a fine input perception and a drive output.

[0051] In this specification, the term "semiconductor" refers in a broad sense to a material that is between good conductors such as metals and insulators such as resins and glass, and refers to a material whose conductivity and resistivity, for example, exhibit values ​​between those of "good conductors such as metals" and "insulators such as resins and glass."

[0052] In the present invention, the semiconductor of the first fiber structure member is not particularly limited in type, and from the perspective of constituent elements, it may be any of a monomer semiconductor, a compound semiconductor, an oxide semiconductor, or an organic semiconductor. In addition, it may be an intrinsic semiconductor equivalent to a high-purity semiconductor material, or it may be an impurity semiconductor to which impurities are added. In addition, from the perspective of carriers, the semiconductor of the first fiber structure member may also be an N-type semiconductor or a P-type semiconductor.

[0053] Although it is just an example, in the first fiber structural member, the component constituting the semiconductor may be at least one selected from the group consisting of carbon (C), silicon (Si), germanium (Ge), gallium (Ga), arsenic (As), indium (In), phosphorus (P), antimony (Sb), aluminum (Al) and nitrogen (N).

[0054] In this specification, "semi-metal" refers to an intermediate material / material whose chemical / physical properties are between metal and non-metal, or a material whose chemical / physical properties take into account both metal and non-metal. It can also be a material called a so-called semi-metal. Although it is just an example after all, the semi-metal element of the first fiber structural component can also be at least one selected from the group consisting of silicon (Si), germanium (Ge), boron (B), arsenic (As), antimony (Sb), tellurium (Te) and astatine (At). As can be seen from the above description, although it also depends on the specific type of element, "semi-metal" and "semiconductor" are interchangeable with each other in this specification. In other words, in the present invention, there is also a situation where the material of the first fiber structural component belongs to both the category of semiconductor and the category of semi-metal, and vice versa.

[0055] In the composite fiber of the present invention, one of the first fiber structural member and the second fiber structural member may be located outside the other of the first fiber structural member and the second fiber structural member and adjacent to the other of the first fiber structural member and the second fiber structural member. Figure 1 As shown in (A) to (C), the second fiber structure member 2 and the first fiber structure member 1 are adjacent to each other, and the second fiber structure member 2 is located relatively outside the first fiber structure member 1. Alternatively, it can be reversed, the first fiber structure member and the second fiber structure member are adjacent to each other, and the first fiber structure member is located relatively outside the second fiber structure member. In either embodiment, due to the relatively large tensile strength and / or elastic modulus of the first fiber structure member, the composite fiber of the present invention can be provided as a fiber (fiber) with further improved strength. In addition, it can be that the first fiber structure member and / or the second fiber structure member have a mode that extends along the axial direction of the composite fiber. In a certain embodiment, both the first fiber structure member and the second fiber structure member extend along the axial direction of the composite fiber. For example, it can also be that the first fiber structure member and the second fiber structure member extend side by side or in parallel with each other along the axial direction of the fiber.

[0056] In addition, the “second fiber structural member including ceramic” may be positioned at a position lower than the “second fiber structural member including ceramic having a volume resistivity of 5×10 -6 ~5×10 6 In this case, in the composite member, the "first fiber structural member containing a material / semiconductor / semimetal having a volume resistivity of 5×10-1" is located on the outside, and in this case, the "second fiber structural member containing ceramics" is used in electrical connection with the first fiber structural member on the inside (or it may be used in electrical connection with the second fiber structural member on the outside to produce the piezoelectric effect involved in the second fiber structural member containing ceramics). Alternatively, the "first fiber structural member containing a material / semiconductor / semimetal having a volume resistivity of 5×10-1" may be located on the outside. -6~5×10 6 Ωm material / semiconductor / semimetallic material” is positioned outside the “second fiber structural member including ceramics”. In this case, in the composite member, the “first fiber structural member including a material / semiconductor / semimetallic material having a volume resistivity of 5×10 -6 ~5×10 6 The first fiber structure member of the material / semiconductor / semi-metal of Ωm is electrically connected to the first fiber structure member on the outside (it can be, similarly, also electrically connected to the second fiber structure member on the inside to produce the piezoelectric effect involved in the second fiber structure member containing ceramics). In this way, the composite fiber of the present invention can be more suitable as a piezoelectric fiber.

[0057] The first fiber structural component 1 contained in the composite fiber is not necessarily limited to a single component. In other words, the first fiber structural component may be composed of a plurality of sub-fiber structural components. For example, the first fiber structural component may be composed of at least two fibrous components. In this way, by being composed of a plurality of sub-fiber structural components, the role of the first fiber structural component that bears the applied stress can be more effectively exerted, and the composite fiber of the present invention can be easily provided as a fiber with higher strength. There is no particular limitation on the number of sub-fiber structural components, and the number of sub-fiber structural components may be, for example, 2 to 50, 2 to 40, 2 to 30, 2 to 20, or 2 to 10 for each composite fiber.

[0058] For example, it could be, Figure 2 In the cross-sectional view shown, a plurality of sub-fiber structural members 1' are arranged as the first fiber structural member 1 in the contour region formed by the second fiber structural member 2. It can also be said that the sub-fiber member 1' (hereinafter also referred to as "the first sub-fiber member") of the first fiber structural member 1 is positioned in the fiber region formed by the second fiber structural member 2 of the composite fiber 10. In this case, the plurality of first sub-fiber members inside the fiber bear the applied stress together, and the high strength of the composite fiber is easily reflected.

[0059] It may be that, when the composite fiber is viewed in cross section, the plurality of first sub-fiber members are arranged symmetrically to each other. Figure 2 As shown, it is also possible that a plurality of first sub-fiber members 1' are arranged in the contour area of ​​the second fiber structure member 2 in order to have a symmetrical relationship such as point symmetry or line symmetry. For such a symmetrical arrangement, the role of the first sub-fiber member that bears the applied stress in the composite fiber can be more effectively exerted. In addition, it is also possible that a plurality of first sub-fiber members extend along the axial direction of the composite fiber. For example, it is also possible that a plurality of first sub-fiber members extend side by side or in parallel with each other along the axial direction of the fiber.

[0060] As described above, the first fiber structural member is preferably a member having a relatively large tensile strength. For example, the tensile strength of the first fiber structural member may be 100 kgf / mm 2 In other words, the tensile strength of the material of the first fiber structural member combined with the second fiber structural member including ceramic in the composite fiber is, for example, 100 kgf / mm 2 Such tensile strength effectively contributes to reducing or preventing inappropriate stress that may be applied to the second fiber structural member including ceramics, and easily provides the composite fiber of the present invention as a high-strength piezoelectric fiber that is not easily broken.

[0061] In a preferred embodiment, the tensile strength of the first fiber structural member is 200 kgf / mm 2 In other words, for the composite fiber combined with the second fiber structural member of ceramic, the “5×10 -6 ~5×10 6 For example, the tensile strength of the first fiber structure member made of a material / semiconductor / semimetallic material with a volume resistivity of Ωm is 200 kgf / mm 2 The above is more effective in achieving a high-strength piezoelectric fiber that is not easily broken. In addition, the upper limit of the tensile strength of the first fiber structure member is not particularly limited, for example, it can be 20000kgf / mm 2 、10000kgf / mm 2 、5000kgf / mm 2 、2500kgf / mm 2 、2000kgf / mm 2 , 1000kgf / mm 2 、800kgf / mm 2 or 500kgf / mm 2 wait.

[0062] In this specification, "tensile strength" refers to the strength obtained by using a tensile tester for a test piece prepared in accordance with JIS R 7606: 2000. For convenience, "tensile strength" may also be a value measured using a strength tester (MST-1 manufactured by Shimadzu Corporation).

[0063] The composite fiber of the present invention has 5×10 -6 ~5×10 6 The first fiber structure component of the material / semiconductor / semi-metal material with a volume resistivity of Ωm can bring about favorable effects in terms of the electrical properties and / or manufacturing process of the composite fiber.

[0064] For example, resistivity adjustment due to element doping and / or defect generation of the semiconductor / semimetal of the first fiber structural member can be achieved, and the desired voltage application can be achieved through the ceramic portion of the second fiber structural member in contact with the first fiber structural member. In other words, the first fiber structural member can be a member at least partially doped with impurities, and due to this, the composite fiber of the present invention can be provided as a piezoelectric fiber that is more preferred from the perspective of voltage application. In addition, the resistivity can also be adjusted by the pattern of the first fiber structural member (e.g., semiconductor / semimetal pattern), which can become a more preferred composite fiber from the perspective of voltage application.

[0065] In a preferred embodiment, the material of the first fiber structure member is composed of carbon and / or silicon. In other words, the volume resistivity of the first fiber structure member is 5×10 -6 ~5×10 6 The material / semiconductor / semi-metal material of Ωm can also be composed of at least one of carbon and silicon. Such a first fiber structural component composed of at least one of carbon and silicon is a preferred component in terms of tensile strength, and more effectively contributes to the realization of high-strength piezoelectric fibers that are not easy to break. In addition, the first fiber structural component composed of at least one of carbon and silicon has excellent heat resistance, so it is easy to bring favorable effects in the manufacturing process of composite fibers. More specifically, the material composed of at least one of carbon and silicon of the first fiber structural component is not easy to change state or does not change state at high temperature, and it is easy to provide a stable process when the ceramic of the second fiber structural component is fired, and it is easy to obtain the desired composite fiber.

[0066] For example, the first fiber structural member of the composite fiber may be mainly composed of carbon, although this is just an example, and may be formed of carbon based on graphite bonds. In addition, the first fiber structural member of the composite fiber may be composed of silicon carbide.

[0067] In a preferred embodiment, the first fiber structural member is made of carbon fiber and / or SiC fiber (silicon carbide fiber). The tensile strength and other strength physical properties of carbon fiber and SiC fiber are significantly higher than those of metal. For example, the tensile strength of metal Ti wire is 48 kgf / mm 2 In comparison, the tensile strength of carbon fiber is 500-700 kgf / mm 2 , the tensile strength of SiC fiber is 300kgf / mm 2. Therefore, for the composite fiber containing carbon fiber and / or SiC fiber as the first fiber structure member (for example, a plurality of first sub-fiber members), the role of the first fiber structure member that bears the applied stress is more effectively played, and the high strength of the composite fiber is easily reflected. In addition, carbon fiber hardly changes its state even at high temperature in a reducing atmosphere. Similarly, SiC fiber does not change its state even at high temperature in air, let alone in a reducing atmosphere. Therefore, when the ceramic of the second fiber structure member is fired, the carbon fiber / SiC fiber is easily stabilized. In addition, such carbon fiber and SiC fiber (silicon carbide fiber) are particularly close to ceramics in thermal expansion coefficient (for example, the thermal expansion coefficient is closer to ceramics than metals such as nickel), so in this respect, the manufacturing process of the composite fiber can become a more desirable process. In other words, when the temperature rises and falls, such as across 1200°C, which is accompanied by the ceramic firing of the second fiber structure member, the difference in expansion and contraction between the first fiber structure member and the second fiber structure member is reduced, and then, the undesirable peeling phenomenon is suppressed, and the desired composite fiber is easily obtained.

[0068] There is no particular limitation on the type of carbon fiber. For example, PAN-based carbon fibers and / or asphalt-based carbon fibers may be used as carbon fibers. PAN-based carbon fibers may be fibers obtained by carbonizing a PAN precursor (polyacrylonitrile fibers), and asphalt-based carbon fibers may be fibers obtained by carbonizing an asphalt precursor (asphalt fibers obtained using coal tar or heavy petroleum fractions as raw materials). Commercially available materials may also be used for such carbon fibers. In addition, the carbon fibers may be provided as extremely fine components having a cross-sectional size of 2 μm to 50 μm, such as 2 μm to 40 μm, 2 μm to 30 μm, 2 μm to 20 μm, 2 μm to 15 μm, 2 μm to 10 μm, 2 μm to 9 μm, 2 μm to 8 μm, or 2 μm to 5 μm, which may easily contribute to the thinning of the composite fiber.

[0069] There is no particular restriction on the type of SiC fiber. Although it is just an example, SiC fiber can also be obtained by gas phase decomposition of an organic silicon compound, or by gas phase decomposition of silicon tetrachloride and hydrocarbons or carbon tetrachloride. Furthermore, SiC fiber can also be obtained by thermally oxidizing silicon-containing carbosilane and then firing it. Such SiC fibers can also use commercially available materials. In addition, SiC fiber can also be provided as an extremely fine component with a cross-sectional size of 2μm to 50μm, such as 2μm to 40μm, 2μm to 30μm, 2μm to 20μm, 2μm to 15μm, 2μm to 10μm, 2μm to 9μm, 2μm to 8μm or 2μm to 5μm, which can easily contribute to the thinning of the composite fiber.

[0070] In the composite fiber of the present invention, as described above, the first fiber structure component can be provided as a component with high tensile strength, but from another perspective, it can be provided as a component with high specific strength ([gf / D]) (for example, a component with higher specific strength than the metal Ti and / or a component with higher specific strength than ceramics such as barium titanate). In this regard, in the present invention, the first fiber structure component can be set as a component with high specific strength whose resistance can be adjusted (for example, by adding dopants to semiconductor materials, etc., the resistance can be adjusted relatively easily). Further, it can also be said that the first fiber structure component can be set as a component with high specific strength whose thermal stability is high and whose resistance can be adjusted. Therefore, for the composite fiber of the present invention involved in a preferred embodiment, it becomes a fiber obtained by compounding with a semiconductor material or a semi-metal material with high thermal stability, adjustable resistance and high specific strength.

[0071] In a preferred embodiment, the second fiber structural member comprises a ceramic sintered body. In other words, in the composite fiber, -6 ~5×10 6 The ceramic of the second fiber structure member combined with the first fiber structure member of a material / semiconductor / semimetal with a volume resistivity of Ωm can also be a sintered body. Such a ceramic sintered body is preferred at least for ceramic fibers, for example, it is preferred in terms of the piezoelectric properties of composite fibers used as piezoelectric fibers. In this specification, a "ceramic sintered body" may be equivalent to a ceramic such as a ceramic crystal fired from at least the "ceramic component" described below. In other words, the "ceramic component" may preferably be a component that can constitute a "ceramic sintered body". In addition, it can also be said that the "ceramic component" is preferably a component that can be contained in the "ceramic sintered body".

[0072] The "ceramic component" contained in the second fiber structural member is not particularly limited as long as it is a component (element) that can constitute ceramics (ceramic crystals, especially metal oxides). For example, it can be selected from lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), yttrium (Y), zirconium (Zr), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), boron (B), aluminum (A), etc. The composite fiber is composed of at least one element selected from the group consisting of titanium (Al), silicon (Si), indium (In), tin (Sn), antimony (Sb), barium (Ba), tantalum (Ta), tungsten (W), lead (Pb), bismuth (Bi), lanthanum (La), cesium (Ce), neodymium (Nd), samarium (Sm), gadolinium (Gd), dysprosium (Dy), holmium (Ho), erbium (Er), oxygen (O), carbon (C), nitrogen (N), sulfur (S), phosphorus (P), fluorine (F), and chlorine (Cl) (hereinafter, sometimes referred to as "ceramic element"). In a certain exemplary embodiment, the ceramic component contained in the composite fiber may be titanium, barium and oxygen, or may be bismuth, sodium, titanium and oxygen.

[0073] In addition, the ceramic component may also include a glass component. As such a glass component, for example, at least one selected from the group consisting of soda-lime glass, potassium glass, borate glass, borosilicate glass, barium borosilicate glass, zinc borate glass, barium borate glass, bismuth borosilicate glass, bismuth zinc borosilicate glass, bismuth silicate glass, phosphate glass, aluminophosphate glass and zinc phosphate glass can be cited.

[0074] In a preferred embodiment, the ceramic of the second fiber structural member is a ceramic selected from the group consisting of barium titanate, sodium bismuth titanate and apatite. In other words, in the composite fiber, the ceramic of the second fiber structural member is selected from the group consisting of barium titanate, sodium bismuth titanate and apatite. -6 ~5×10 6 The ceramic of the second fiber structural member of the combination of the first fiber structural member of the material / semiconductor / semi-metal material with a volume resistivity of Ωm can also be a ceramic material selected from the group consisting of barium titanate, sodium bismuth titanate and apatite. For example, ceramic barium titanate, sodium bismuth titanate and apatite can also be sintered bodies. Such ceramics can be obtained by firing, and the effects of the present invention can be easily reflected. In other words, firing is accompanied by a high-temperature process, but the first fiber structural member of the composite fiber of the present invention can present preferred characteristics in its thermal stability and / or thermal expansion coefficient during the firing process. Therefore, the ceramic fiber composed of a ceramic sintered body as described above is more stable and / or high-strength.

[0075] The ceramic sintered body may also contain grains or crystallites. The size of the grains of the ceramic sintered body is not particularly limited. The size of the grains of the ceramic sintered body may be, for example, 0.1 μm to 10 μm. In this specification, the size of the grains refers to the maximum size of the grains or crystallites when viewed in cross section. The ceramic sintered body may be a polycrystal of ceramic (or ceramic component).

[0076] The size of the crystal grains that may be contained in the ceramic sintered body may also depend on the ceramic component, for example, the particle size of the powder of the ceramic component before firing may also be 0.05 μm to 5 μm. The presence of crystal grains in the composite fiber can be confirmed by using an image obtained by photographing the range of the region containing the object using a transmission electron microscope, a scanning electron microscope, a scanning ion microscope, etc., and the presence or absence of crystal grains can be distinguished by observing the contrast difference caused by the difference in crystal orientation.

[0077] For example, when the ceramic of the composite fiber is composed of barium titanate, sodium bismuth titanate, or apatite, the second fiber structural member may include barium titanate (BaTiO3) (BT), sodium bismuth titanate ((Bi 1 / 2 Na 1 / 2 )TiO3)(BNT), or grains or crystallites of apatite.

[0078] In addition, the apatite of the second fiber structural member is not particularly limited in specific type as long as it is a substance that usually belongs to its category. In the case where apatite is preferably used in the composite fiber, the second fiber structural member contains apatite and / or a component derived from it. Apatite can also be a ceramic of a calcium phosphate-based functional inorganic material, or a substance with phosphorus (P) and calcium (Ca) as the main components. In the case where the second fiber structural member contains apatite, it is characterized in that: although apatite is a ceramic that is usually identified as a biomaterial, the piezoelectric fiber uses the ceramic. In a preferred embodiment, apatite used as a ceramic biomaterial can also be used for the second fiber structural member. If an apatite material is used for the second fiber structural member like this, a more preferred ceramic fiber is easily obtained. For example, if an apatite material is used for the second fiber structural member, it is easy to give the second fiber structural member high mechanical strength and fracture toughness, and it is easy to appropriately bring electronic properties such as the performance / control of charge retention ability to the composite fiber.

[0079] For example, the apatite for the second fiber structure member may also be at least one selected from the group consisting of fluorapatite, chlorapatite, hydroxyapatite, and oxygen apatite. Fluorapatite (FAp) is represented by the chemical formula: Ca5(PO4)3F, and may also be referred to as fluorapatite (Japanese: フッ素アパタイト) or fluorapatite (Japanese: フッ素リン灰石). "Chlorapatite" (CAp) is represented by the chemical formula: Ca5(PO4)3Cl, and is also referred to as chlorapatite (Japanese: 塩素アパタイト) or chlorapatite (Japanese: 塩素リン灰石), etc. The type of hydroxyapatite (HAp) is not particularly limited. For example, hydroxyapatite (HAp) may also be represented by the chemical formula: Ca5(PO4)3(OH)2, and may also be referred to as hydroxyapatite (Japanese: 水酸アパタイト) or hydroxyapatite (Japanese: 水酸リン灰石), etc. In addition, oxygen apatite (OHA) may also be represented by the chemical formula: Ca5(PO4)3O. Here, as the apatite for the second fiber structure member, hydroxyapatite and / or oxygen apatite is preferred. Therefore, the second fiber structure member may contain hydroxyapatite and / or oxygen apatite or components derived from them. Such hydroxyapatite and oxygen apatite are generally known as biomaterials. Therefore, the composite fiber formed of hydroxyapatite and / or oxygen apatite is characterized by using bioceramics for piezoelectric fibers. The hydroxyapatite and / or oxygen apatite or components derived from them in the second fiber structure member of the composite fiber can not only impart high mechanical strength and fracture toughness to the composite fiber, but also impart excellent electronic properties such as charge retention ability to the composite fiber.

[0080] The ceramic of the second fiber structure member may also be composed of a composite material compounded with a resin. For example, it may be that the second fiber structure member is formed by molding a raw material containing a ceramic component and a resin component. The resin refers to a polymer material, and there is no particular limitation as long as it is a polymer material, and thermoplastic resins and / or thermosetting resins, etc. can be appropriately used. For example, phenolic resin, epoxy resin, bismaleimide resin, polypropylene resin, polyimide resin, polyamideimide resin, and / or acrylonitrile resin, etc. can be used. Such resin materials may also be materials in which one or more sterically hindered amine-based additives or triazine-based additives are incorporated. The ratio of ceramic to resin (ceramic / resin) in the composite material may be, for example, 99 / 1 to 1 / 99 on a volume basis. Although it is only an example after all, such a ratio (ceramic / resin) may also be in the range of 64 / 36 to 1 / 99, 30 / 70 to 1 / 99, or 20 / 80 to 1 / 99.

[0081] The cross-sectional dimensions of the composite fiber of the present invention are not particularly limited as long as they are of a size equivalent to the fiber. In other words, it is also possible that, when viewed in section, a composite fiber of a preferred embodiment has a fiber dimension, such as a cross-sectional dimension of the order of μm. For example, the fiber diameter of the composite fiber may be 500 μm or less (particularly 1 μm or more and 500 μm or less), and therefore, it may be 400 μm or less (particularly 1 μm or more and 400 μm or less), 300 μm or less (particularly 1 μm or more and 300 μm or less), 200 μm or less (particularly 1 μm or more and 200 μm or less), and in a certain example, it may be 50 μm to 100 μm, etc. In the present invention, due to the first fiber structural component as described above, it is easier to achieve a thinner diameter (smaller size) than the existing PZT fiber. In addition, in this specification, the "fiber diameter" of the composite fiber refers to the maximum dimension (e.g., diameter) in the cross section in a direction perpendicular to the axial direction of the fiber.

[0082] In the composite fiber, the cross-sectional area ratio between the first fiber structure member and the second fiber structure member is not particularly limited. For example, the value of the area of ​​the first fiber structure member / the area of ​​the second fiber structure member when viewed in cross section may also be 1 / 99 to 99 / 1. Although this is only an example, the cross-sectional area of ​​the first fiber structure member / the cross-sectional area of ​​the second fiber structure member may also be 1 / 8 to 8 / 1, etc.

[0083] The composite fiber of the present invention preferably exhibits a strength that is improved over that of the existing PZT fiber. In other words, it is a composite fiber that can be used as a ceramic fiber of a piezoelectric fiber and has a more suitable strength. For example, for the composite fiber of the present invention, the tensile strength (e.g., elongation at break load) of the entire fiber is preferably 5 kgf / mm 2 Above, for example 6kgf / mm 2 Above, 10kgf / mm 2 Above, 14kgf / mm 2 Above or 20kgf / mm 2 Although this is just an example, in a preferred embodiment, the tensile strength (breaking elongation load) of the entire fiber of the composite fiber of the present invention is 50 kgf / mm 2 Above and 400kgf / mm 2 the following.

[0084] The conjugate fiber of the present invention can be embodied in various forms.

[0085] (Mutual arrangement of the first fiber structural member and the second fiber structural member - core-sheath structure 1)

[0086] The composite fiber of the present invention can be in various forms as long as the first fiber structure member and the second fiber structure member satisfy a mutually adjacent positional relationship. It is also possible that, as described above, the first fiber structure member and the second fiber structure member are adjacent to each other so that one of the first fiber structure member and the second fiber structure member is located at an outer side than the other of them. In addition, it is also possible that, when viewed in section, the first fiber structure member is at least partially surrounded by the second fiber structure member.

[0087] For example, the composite fiber composed of the first fiber structural member and the second fiber structural member may have a core-sheath structure. Figure 3 In the illustrated method, the core is composed of the first fiber structure member 1, and the sheath is composed of the second fiber structure member 2. In particular, in the illustrated method, the first fiber structure member 1 of the core occupies a relatively larger cross-sectional area than the second fiber structure member 2 of the sheath. In such a method, the proportion of the portion that effectively bears the stress applied by the composite fiber (i.e., the portion of the first fiber structure member with high tensile strength) is increased, so when an external force is applied to the composite fiber, it is not easy to apply inappropriate stress to the second fiber structure member and it is not easy to break. In other words, it is easy to bring about a high-strength piezoelectric fiber.

[0088] (Mutual arrangement of the first fiber structural member and the second fiber structural member - core-sheath structure 2)

[0089] The composite fiber of this embodiment has a core-sheath structure as described above, but the second fiber structure member 2 of the sheath portion occupies a relatively larger cross-sectional area than the first fiber structure member 1 of the core portion (see Figure 4 ). In other words, Figure 4 As in the exemplary embodiment of FIG. 1 , the cross-sectional outline size of the first fiber structure member 1 provided as the core is less than half of the cross-sectional outline size of the second fiber structure member 2 provided as the sheath (i.e., the overall cross-sectional size of the composite fiber 10). In such an embodiment, in particular, as a piezoelectric fiber, a composite fiber that exhibits a more efficient piezoelectric effect can be easily obtained.

[0090] (Mutual arrangement of the first fiber structural member and the second fiber structural member - first fiber structural member of multiple cores / fine fibers)

[0091] The composite fiber of this embodiment has a core-sheath structure similar to the above, but the first fiber structural member of the core portion is not a single structure but a multiple structure. Figure 5 The composite fiber 10 shown in the figure has two fiber structural members 1 that serve as cores. In addition, the composite fiber 10 is not limited to two in particular, and may also be Figure 6 Such an exemplary embodiment is a method having a particularly fine first fiber structure member. In other words, in Figure 6 In the manner shown, a plurality of first fiber structural members 1' having a fine diameter are disposed in the fiber 10. For example, as shown in the figure, sub-fiber members 1' of the first fiber structural member 1 can be disposed in parallel with each other in the fiber region formed by the second fiber structural member 2. In such a manner, a plurality of first fiber structural members (i.e., a plurality of sub-fiber members 1' having a large tensile strength) jointly bear the applied stress of the composite fiber, and therefore, a high-strength piezoelectric fiber can be easily obtained.

[0092] In addition, it is considered that there are various configurations of the plurality of first fiber structural members when viewed in cross section. In the present invention, the first fiber structural member such as carbon fiber and / or SiC fiber can be provided as a particularly fine fiber material, and therefore, it is easy to have a plurality of configurations in a single composite fiber. Figure 6 As shown, the plurality of first fiber structural members (ie, the plurality of sub-fiber members 1 ′) may also have a mutually symmetrical arrangement relationship, for example.

[0093] (Mutual arrangement of the first fiber structural member and the second fiber structural member - two-axis arrangement)

[0094] This method is a method in which the composite fiber does not have a single axis. Figure 7 The composite fiber 10 shown has a configuration in which the fiber as a whole has two axes.

[0095] In such a composite fiber 10, one of the first fiber structural member and the second fiber structural member may be positioned relatively outside, and the other may be positioned relatively inside. Figure 7 In the composite fiber 10 shown, the second fiber structure member 2 is positioned relatively outside, and the first fiber structure member 1 is positioned relatively inside. From another perspective, the fiber body is formed in a manner that the first fiber structure member 1 and the second fiber structure member 2 are adjacent to each other in a direction orthogonal to the axial direction of the fiber. Figure 7 In the embodiment shown, high-strength materials such as carbon and / or SiC can be positioned in regions of the composite fiber that are more subjected to tension / compression, and thus piezoelectric fibers that are strong against bending (eg, left-right bending) can be easily provided.

[0096] (Doping method of the first fiber structural member)

[0097] Such a method is a method in which the first fiber structure component in the composite fiber is at least partially doped with impurities. For example, in the composite fiber, the first fiber structure component containing the semiconductor material is at least partially doped with impurities. By doping with impurities (injection of additives, ions or impurities), the resistance of the semiconductor material of the first fiber structure component can be adjusted, so it is easy to obtain the desired composite fiber in terms of resistivity and the like. The type of dopant (injected additive, ion or impurity) is not particularly limited. For example, it can also be a dopant selected from the group consisting of boron, nitrogen, aluminum and phosphorus.

[0098] In a preferred embodiment, the first fiber structure member is at least partially composed of a semiconductor such as an N-type semiconductor and / or a P-type semiconductor. For example, the first fiber structure member may be at least partially composed of an N-type semiconductor or a P-type semiconductor obtained by doping an intrinsic semiconductor with impurities.

[0099] It is also possible that, particularly when the first fiber structural member is composed of a semiconductor, a doped region (e.g., a doped layer) exists at the interface between the semiconductor of the first fiber structural member and the ceramic of the second fiber structural member. In such a composite fiber, the composite fiber of the present invention can be provided as a fiber that functions by applying a voltage at the semiconductor / ceramic interface via a doped layer of a metal or semiconductor. In addition, it is also possible that, when a doped region (e.g., a doped layer) is provided, a gate electrode element, a drain electrode element, a source electrode element, etc. are appropriately provided as associated elements.

[0100] (Changes in electronic component design)

[0101] The composite fiber of the present invention may have, for example, Figure 8 (a)~ Figure 8 A structure as shown in (d).

[0102] Figure 8 The composite fiber 20 shown in (a) has a concentric structure. In other words, it has a circular cross section and has a structure in which the center portion 21 and the outer portion 22 are arranged in a substantially concentric shape. The cross-sectional shape shown in the figure is circular and concentric, but it is not limited to this.

[0103] In the composite fiber 20, one of the central portion 21 and the outer portion 22 forming concentric circles may be composed of one of the "semiconductor / semimetal first fiber structural component" and the "ceramic second fiber structural component", or the other of the central portion 21 and the outer portion 22 may be composed of the other of the "semiconductor / semimetal first fiber structural component" and the "ceramic second fiber structural component". Alternatively, in the composite fiber 20, the "semiconductor / semimetal first fiber structural component" and the "ceramic second fiber structural component" are in close contact with each other to form an interface. Figure 8 In (a), the fiber diameter D shown in the schematic diagram obtained by cutting at AA' a (The maximum dimension or the maximum diameter) may be, for example, 500 μm or less, and more specifically, may be 1 μm or more and 500 μm or less.

[0104] Figure 8 The composite fiber 30 shown in (b) has a structure in which a part of its outer portion is cut away. In other words, the composite fiber 30 has a structure in which an outer portion 32a having a substantially C-shaped (or substantially crescent-shaped) cross section and an outer portion 32b having a substantially inverted C-shaped (or substantially crescent-shaped) cross section (hereinafter, the outer portions 32a and 32b are collectively referred to as "outer portions 32") are arranged at intervals on a center portion 31 having a substantially circular cross section. In addition, the cross-sectional shape of the composite fiber 30 is not limited to the shape shown in the figure.

[0105] In the composite fiber 30, one of the central portion 31 and the outer portion 32 is composed of one of the "semiconductor / semimetal first fiber structural member" and the "ceramic second fiber structural member", and the other of the central portion 31 and the outer portion 32 is composed of the other of the "semiconductor / semimetal first fiber structural member" and the "ceramic second fiber structural member". In the composite fiber 30, the "semiconductor / semimetal first fiber structural member" and the "ceramic second fiber structural member" may be in close contact with each other to form an interface.

[0106] The “semiconductor / semimetal” or “ceramic” contained in the outer portion 32 may be the same or different in the outer portions 32 a and 32 b .

[0107] Figure 8 The fiber diameter D shown in the schematic diagram obtained by cutting at BB' in (b) b (The maximum dimension or the maximum diameter) may be, for example, 500 μm or less, and more specifically, may be 1 μm or more and 500 μm or less.

[0108] Figure 8The composite fiber 40 shown in (c) has a structure in which half of its outer portion is cut away. In other words, the composite fiber 40 has a structure in which the outer portion 42 having a substantially C-shaped (or substantially crescent-shaped) cross section is arranged partially in the center portion 41 having a substantially circular cross section. In addition, the cross-sectional shape of the composite fiber 40 is not limited to the shape shown in the figure.

[0109] In the composite fiber 40, one of the central portion 41 and the outer portion 42 is composed of one of the "semiconductor / semimetal first fiber structural member" and the "ceramic second fiber structural member", and the other of the central portion 41 and the outer portion 42 is composed of the other of the "semiconductor / semimetal first fiber structural member" and the "ceramic second fiber structural member". In the composite fiber 40, the "semiconductor / semimetal first fiber structural member" and the "ceramic second fiber structural member" may be in close contact with each other to form an interface.

[0110] Figure 8 The fiber diameter D shown in the schematic diagram obtained by cutting at CC' in (c) is c (The maximum dimension or the maximum diameter) may be, for example, 500 μm or less, and more specifically, may be 1 μm or more and 500 μm or less.

[0111] Figure 8 The composite fiber 50 shown in (d) has a structure with an intermediate layer. In other words, the composite fiber 50 has a substantially circular cross-section, and has a structure in which a central portion 51, an outer portion 52, and an intermediate layer 53 disposed therebetween are substantially arranged in a concentric circle. In addition, the cross-sectional shape of the composite fiber 50 is not limited to a circle or a concentric circle.

[0112] In the composite fiber 50, one of the central portion 51 and the outer portion 52 is composed of one of the "first fiber structural member of semiconductor / semimetal" and the "second fiber structural member of ceramic", and the other of the central portion 51 and the outer portion 52 is composed of the other of the "first fiber structural member of semiconductor / semimetal" and the "second fiber structural member of ceramic". In addition, the material of the intermediate layer 53 is not particularly limited, and may be composed of at least one substance selected from the group consisting of metal, ceramic, semimetal and semiconductor. Alternatively, in the composite fiber 50, the "first fiber structural member of semiconductor / semimetal provided in one of the central portion 51 and the outer portion 52" and the "second fiber structural member of ceramic provided in the other of the central portion 51 and the outer portion 52" are in contact with each other via the intermediate layer 53.

[0113] Figure 8 The fiber diameter D shown in the schematic diagram obtained by cutting at D-D' in (d) is d(The maximum dimension or the maximum diameter) may be, for example, 500 μm or less, and more specifically, may be 1 μm or more and 500 μm or less.

[0114] The method for producing the composite fiber of the present invention is not particularly limited, and the composite fiber can be appropriately produced by applying a conventional ceramic firing technique or the like.

[0115] Although this is just an example, for example, the above-mentioned “having 5×10 -6 ~5×10 6 A paste made of a material / semiconductor / semimetallic material having a volume resistivity of Ωm and a sintering aid, auxiliary material, binder resin, solvent, dispersant and / or plasticizer added as needed, and a paste made of a raw material containing the above-mentioned ceramic component (ceramic element) and a sintering aid, auxiliary material, binder resin, solvent, dispersant and / or plasticizer added as needed (hereinafter also referred to as "ceramic raw material paste") are appropriately formed and fired (for example, normal pressure firing or pressure firing, etc.), thereby manufacturing a composite fiber in which the first fiber structural member and the second fiber structural member are integrally adjacent to each other. At this time, for example, each paste can be formed into a desired shape using a multi-nozzle (a nozzle for composite spinning such as a double nozzle or a triple nozzle), a molding die, etc.

[0116] In the case where the second fiber structure member is formed by firing, the first fiber structure member may also be formed by firing. Therefore, the second fiber structure member may also be formed by firing. -5 ~1×10 6 The composite fiber of the present invention is obtained by co-sintering "a component of a material / semiconductor / semimetallic material with a volume resistivity of Ωm" and "a ceramic component". In the case of co-sintering, it is preferred that the second fiber structure member becomes a sintered body, and the first fiber structure member also becomes a sintered body. In such a case, the interface formed by the sintered body of the first fiber structure member and the sintered body of the second fiber structure member may be composed of grains. In addition, in a preferred embodiment, such an interface may have "surface roughness" and may be an interface that is not a straight line but a non-straight line when viewed in section (or an interface that has roughness, line roughness, surface roughness or unevenness). In other words, the interface between the first fiber structure member and the second fiber structure member may have a shape like a broken line when viewed in section. Such an interface can effectively contribute to the prevention of interlayer delamination between the first fiber structure member and the second fiber structure member and / or can contribute to the improvement of the strength of the composite fiber.

[0117] In addition, in the case where the first fiber structural member is composed of composite fibers such as carbon fibers and / or SiC fibers, commercially available carbon fibers and / or SiC fibers may be used. In other words, the desired composite fibers can be obtained by appropriately combining such carbon fibers and / or SiC fibers with the above-mentioned ceramic raw material paste and firing them, or by combining such carbon fibers and / or SiC fibers with a resin raw material containing a ceramic component and performing a molding process, etc., the desired composite fibers can also be obtained.

[0118] The above descriptions of the embodiments of the present invention are merely typical examples, and therefore, it should be easily understood by those skilled in the art that the present invention is not limited thereto, and that various embodiments exist within the scope of the present invention.

[0119] For example, in the above description, a drawing is used in which the first fiber structure member and the second fiber structure member are adjacent to each other in the radial direction of the composite fiber, but the present invention is not necessarily limited to this. Alternatively, the composite fiber may have a structure in which the first fiber structure member and the second fiber structure member are arranged and adjacent to each other in the axial direction of the fiber. Fig. 9 In the composite fiber 60 shown, the first fiber structural member 61 and the second fiber structural member 62 are arranged in the axial direction of the fiber and are combined so as to contact each other.

[0120] In addition, in the above description, the drawings in which the composite fiber has a concentric structure are often used, but the present invention is not necessarily limited to this. The composite fiber may also have a sandwich structure. In other words, it may also be a mode in which one of the first fiber structure member and the second fiber structure member is sandwiched by the other one of them. Fig.10 The composite fiber 70 shown has a configuration in which a ceramic second fiber structure member 72 is sandwiched between semiconductor / semimetal first fiber structure members 71. In such a composite fiber, the cross-sectional shape may be rectangular or square as shown in the figure.

[0121] Furthermore, the first fiber structure component and the second fiber structure component of the composite fiber involved in the present invention can also be specified as structures of semiconductor / semi-metallic materials and ceramic materials only. In other words, in a composite fiber involved in a preferred embodiment of the present invention, the first fiber structure component is only composed of semiconductor or semi-metallic materials, and the second fiber structure component is only composed of ceramic materials. In addition, in the present invention, for the first fiber structure component and the second fiber structure component, the presence of components (for example, trace components or extremely trace components, etc.) that may be inevitably or accidentally mixed in when these components are formed and / or when the composite fiber is manufactured can be allowed.

[0122] Industrial Applicability

[0123] The composite fiber of the present invention can be used as various piezoelectric fibers, or can also be used as fibrous electronic components, etc. Although it is just an example, the composite fiber of the present invention can be used in sensors, especially vibration sensors, actuators, etc. used in structures such as buildings, automobiles, ships and / or aircraft.

[0124] Description of Reference Numerals

[0125] 1...the first fiber structural member; 1'...a sub-fiber structural member (a sub-fiber member of the first fiber structural member); 2...the second fiber structural member; 10, 20, 30, 40, 50, 60, 70...composite fibers; 21, 31, 41, 51...a central portion; 22, 32, 42, 52...an outer portion; 53...an intermediate portion; 61...the first fiber structural member; 62...the second fiber structural member; 71...the first fiber structural member; 72...the second fiber structural member; 100...PZT fibers; 101...a metal wire / a metal thin wire; 102...a PZT thin layer / a PZT film; 103...a nozzle; 104...a wire guide; 105...a PZT paste; 200...a smart substrate; 201...a carbon fiber reinforced plastic (CFRP) prepreg; 202...a structure.

Claims

1. A composite fiber, characterized in that: With a volume resistivity of 5×10 -6 ~5×10 6 A first fiber structural member made of a material having a diameter of Ωm and a second fiber structural member made of ceramic, wherein the first fiber structural member and the second fiber structural member are adjacent to each other to form a fiber body.

2. A composite fiber, characterized in that: A first fiber structure member including a semiconductor or semimetal material and a second fiber structure member including ceramics are provided, wherein the first fiber structure member and the second fiber structure member are adjacent to each other to form a fiber body.

3. The composite fiber according to claim 1 or 2, characterized in that The first fiber structural member and the second fiber structural member are adjacent to each other such that one of the first fiber structural member and the second fiber structural member is located outside the other of the first fiber structural member and the second fiber structural member.

4. The composite fiber according to any one of claims 1 to 3, characterized in that In cross-sectional view, the first fiber structural component is at least partially surrounded by the second fiber structural component.

5. The composite fiber according to any one of claims 1 to 4, characterized in that The first fiber structural member is composed of a plurality of sub-fiber structural members.

6. The composite fiber according to claim 5, characterized in that In cross-sectional view, the plurality of sub-fiber structural members are arranged within a contour region formed by the second fiber structural member.

7. The composite fiber according to any one of claims 1 to 6, characterized in that The tensile strength of the first fiber structural member is 100 kgf / mm 2 above.

8. The composite fiber according to any one of claims 1 to 7, characterized in that The tensile strength of the first fiber structural member is 200 kgf / mm 2 above.

9. The composite fiber according to any one of claims 1 to 8, characterized in that The material of the first fiber structure member is composed of carbon and / or silicon.

10. The composite fiber according to any one of claims 1 to 9, characterized in that The first fiber structure member is at least partially doped with impurities.

11. The composite fiber according to any one of claims 1 to 10, characterized in that The second fiber structural member includes a ceramic sintered body.

12. The composite fiber according to any one of claims 1 to 11, characterized in that The ceramic component is composed of at least one element selected from the group consisting of lithium Li, sodium Na, potassium K, magnesium Mg, calcium Ca, strontium Sr, barium Ba, yttrium Y, zirconium Zr, titanium Ti, vanadium V, chromium Cr, manganese Mn, iron Fe, cobalt Co, nickel Ni, copper Cu, zinc Zn, boron B, aluminum Al, silicon Si, indium In, tin Sn, antimony Sb, barium Ba, tantalum Ta, tungsten W, lead Pb, bismuth Bi, lanthanum La, cesium Ce, neodymium Nd, samarium Sm, gadolinium Gd, dysprosium Dy, holmium Ho, erbium Er, oxygen O, carbon C, nitrogen N, sulfur S, phosphorus P, fluorine F and chlorine Cl.

13. The composite fiber according to any one of claims 1 to 12, characterized in that The ceramic is a ceramic selected from the group consisting of barium titanate, sodium bismuth titanate and apatite.

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